Reactions of trinuclear platinum clusters with electrophiles: ionisation isomerism with [Pt3(μ2-I)(μ-PPh2)2(PPh3)3]I and [Pt3(μ-PPh2)2I2(PPh3)3]. Structures of [Pt3(μ2-Cl)(μ-PPh2)2(PPh3)3]PF6, [Pt3(μ-PPh2)2I2(PPh3)3] and of the Pt–Ag cluster [Pt3{μ3-AgBF4}(μ2-I)(μ-PPh2)2(PPh3)3]BF4

Abstract

A reaction of the 44 electron cluster [Pt₃(μ-PPh₂)₃Ph(PPh₃)₂] (1) with wet AgBF₄ afforded the cationic cluster [Pt₃(μ₂-OH)(μ-PPh₂)₂(PPh₃)₃]BF₄ (3(BF₄)) which slowly transformed into [Pt₃(μ₂-Cl)(μ-PPh₂)₂(PPh₃)₃]BF₄ (4(BF₄)) upon recrystallization from CH₂Cl₂. These 44 electron clusters have been characterized by ³¹P{¹H} NMR, and the crystal structure of 4(PF₆) has been determined by X-ray diffraction, as well as that of [Pt₃(μ-PPh₂)₂I₂(PPh₃)₃] (5), which was obtained by recrystallization of the known cluster [Pt₃(μ₂-I)(μ-PPh₂)₂(PPh₃)₃]I (2(I)) from toluene and represents a neutral formula isomer of the latter. In addition, we have prepared the adducts of cluster 1 containing the moieties [Cu(NCMe)₂]⁺ and [Au(PPh₃)]⁺ in 6 and 7, respectively, and on the basis of their spectroscopic data, it was concluded that these complexes have similar structures to that previously established for the adduct of 1 with Ag(TFA) (TFA = OC(O)CF₃), [Pt₃{μ₃-Ag(TFA)}(μ-PPh₂)₃Ph(PPh₃)₂] (8). The cationic clusters in 3(BF₄) and 4(BF₄) react with Ag(TFA) to afford cationic adducts in [Pt₃{μ₃-Ag(TFA)}(μ₂-X)(μ-PPh₂)₂(PPh₃)₃]BF₄ (9(BF₄), X = OH; 10(BF₄), X = Cl). The structure of the mixed-metal cluster [Pt₃(μ₃-AgBF₄)(μ₂-I)(μ-PPh₂)₂(PPh₃)₃]BF₄ (11(BF₄)), obtained by reaction of the complex 2(I) with AgBF₄, was determined by X-ray diffraction.